Word Frequency Approximation for Chinese Using Raw, MM-Segmented and Manually Segmented Corpora

Word frequencies play important roles in many NLP-related applications. Word frequency estimation for Chinese remains a big challenge due to the characteristics of Chinese. An underlying fact is that a perfect word-segmented Chinese corpus never exists, and currently we only have raw corpora, which can be of arbitrarily large size, automatically word-segmented corpora derived from raw corpora, and a number of manually word-segmented corpora, with relatively smaller size, which are developed under various word segmentation standards by different researchers. In this paper we propose a new scheme to do word frequency approximation by combining the factors above. Experiments indicate that in most cases this scheme can benefit the word frequency estimation, though in other cases its performance is still not very satisfactory.